The present invention relates to an adhesive system based on a nonreactive thermoplastic hot melt adhesive, particularly for use in wood processing and furniture processing, with the use of metallocene-catalytically manufactured copolymers as well as to their use particularly in wood processing and furniture processing, particularly for purposes of profile coating or edge bonding, and also in other application fields (for example, in the transport industry and construction industry, in the textile industry, in the general assembly sector, etc.). Synonyms for the term hot melt adhesive that are used below are “hotmelt,” “thermal fusion adhesive,” or similar terms.
According to the state of the art, EVA copolymers (i.e., ethylene/vinyl acetate copolymers) dominate the market portion of thermoplastic hot melt adhesives (hotmelts) by far. The largest application field for thermoplastic hot melt adhesives is the paper industry and packaging industry, and, in this connection, particularly for the purposes of so-called cardboard closure. In addition, ethylene vinyl acetate-based thermoplastic hot melt adhesive systems are used in wood processing and furniture processing.
The EVA-based hot melt adhesives that are used generally in wood processing and furniture processing, however, require, on the one hand, relatively high processing temperatures, namely temperatures generally in the range of 180-210° C., which is detrimental when gluing heat-sensitive substrates. On the other hand, systems based on ethylene/vinyl acetate copolymers (EVA) are limited insofar as increasing vinyl acetate contents decrease the compatibility with other formulation components of the system, although they generally improve the elastomer performance.
Occasionally, polyolefin-based systems are also used. For example, linear low density polyethylene (LLDPE) and low density polyethylene (LDPE) are used as base polymers in a multitude of hot melt adhesives, particularly for box gluing and cardboard gluing. Linear low density polyethylene and low density polyethylene, however, present the drawback, when used as base materials or raw materials for adhesives, that, due to their crystalline nature, they tend to be very stiff and present unsatisfactory low temperature properties. For the rest, such adhesives present a limited hot adhesive capacity, which leads to low glue dissolution temperatures. In particular, due to the poor oil retention capacity, polyethylene also presents a limited usability as a base polymer in the formulation of contact adhesives.
Moreover, hot melt adhesive compositions that are known from the state of the art contain polyolefin waxes and are manufactured with the help of metallocene catalysts (see, for example, DE 103 23 617 A1). Such adhesive systems are indeed suitable for the paper industry and packaging industry, but not for use in wood processing and furniture processing, particularly due to the only relatively small cohesion, and the poor initial adhesion, and also because of the relatively short open times or processing times.
In principle, the hot melt adhesives based on metallocene-catalytically manufactured polyolefins known from the state of the art cannot be used in the present target sectors, particularly not in wood processing and furniture processing, because they present insufficient cohesion with respect to the initial strength and final strength, and only insufficient open times or processing times, so that they cannot be used at all, for example, for gluing processes in the wood industry and furniture industry.
The present invention is therefore based on the problem of providing an adhesive system based on a nonreactive thermoplastic hot melt adhesive, which at least partially avoids, or at least partially decreases the above described disadvantages of the state of the art.
An additional problem of the present invention is to produce an adhesive system based on a nonreactive thermoplastic hot melt adhesive, which is particularly suited for use in wood processing and furniture processing, and also in other application fields.